/// <summary>
/// Analyzes the song data for beat information
/// </summary>
/// <returns>A beatmap of the song.</returns>
/// <param name="data">Raw data.</param>
/// <param name="clip">Audio clip to analyze.</param>
/// <param name="thresholdModifier">Threshold value modifier</param>
public BeatMap AnalyzeData(double[] data, AudioClip clip, float thresholdModifier)
{
_beatList = new BeatMap(clip.name, clip.length);
int numParts = (int)clip.length;
int partitionSize = (data.Length + 1) / numParts;
//We only care about the magnitude of our data, so we get the absolute values before doing analysis
data = data.ToList().Select(i => (double)Mathf.Abs((float)i)).ToArray();
for (int i = 0; i < data.Length - (int)(partitionSize); i += (int)(partitionSize))
{
//finds the average value of the sub-partition starting at index i and of size partitionSize
double avg = data.Skip(i).Take(partitionSize).Average();
//finds the highest energy sample in the current partition
//int largest = i;
//calculate the average energy variance in the partition
double variance = 0;
for (int j = 0; j < partitionSize; j++)
{
variance += (data[i + j] - avg) * (data[i + j] - avg);
}
variance /= partitionSize;
//calculate the base threshold using some magic numbers and the variance
double thresh = (-0.0025714 * variance) + 1.5142857;
thresh *= thresholdModifier;
//if the any sample is threshold percent larger than the average, then we mark it as a beat.
for (int j = 0; j < partitionSize; j++)
{
if (data[i + j] > thresh * avg)
{
_beatList.AddBeat(((float)(i + j) / data.Length) * clip.length, 1f, data[i + j]);
}
}
}
//eliminate double positives (the same beat occurring in two overlapping partitions, for example) by removing beats with extremely similar timestamps
for (int i = 0; i < _beatList.beats.Count - 1; i++)
{
if ((_beatList.beats[i + 1].timeStamp - _beatList.beats[i].timeStamp) < .1)
{
if (_beatList.beats[i + 1].energy > _beatList.beats[i].energy)
{
_beatList.beats.RemoveAt(i);
}
else
{
_beatList.beats.RemoveAt(i + 1);
}
i--;
}
}
return(_beatList);
}
/// <summary>
/// Writes a beatmap to xml file from BPM and song length.
/// </summary>
/// <param name="name">Xml file name.</param>
/// <param name="bpm">Beats per minute.</param>
/// <param name="numBeats">Number of beats.</param>
public static void BeatMapFromBPM(string name, float bpm, int numBeats)
{
float beatStep = 60f / bpm;
float length = (float)numBeats * beatStep;
BeatMap beats = new BeatMap(name, length);
for (float i = 0f; i < length; i += beatStep)
{
beats.AddBeat(i, 1f, 1);
}
BeatMapSerializer.BeatMapWriter.WriteBeatMap(beats);
Debug.LogFormat("Coda: Created beatmap {0} with BPM of {1} and running time of {2} seconds ({3} beats long).", name, bpm, length, numBeats);
}
/// <summary>
/// Analyzes the song data for beat information
/// </summary>
/// <returns>A beatmap of the song.</returns>
/// <param name="data">Raw data.</param>
/// <param name="clip">Audio clip to analyze.</param>
/// <param name="thresholdModifier">Threshold value modifier</param>
public BeatMap AnalyzeData(double[] data, AudioClip clip, float thresholdModifier)
{
_beatList = new BeatMap(clip.name, clip.length);
int numParts = (int)clip.length;
int partitionSize = (data.Length+1)/numParts;
//We only care about the magnitude of our data, so we get the absolute values before doing analysis
data = data.ToList().Select(i => (double)Mathf.Abs((float)i)).ToArray();
for(int i = 0; i < data.Length-(int)(partitionSize); i += (int)(partitionSize)) {
//finds the average value of the sub-partition starting at index i and of size partitionSize
double avg = data.Skip(i).Take(partitionSize).Average();
//finds the highest energy sample in the current partition
//int largest = i;
//calculate the average energy variance in the partition
double variance = 0;
for(int j = 0; j < partitionSize; j++)
{
variance += (data[i + j] - avg) * (data[i + j] - avg);
}
variance /= partitionSize;
//calculate the base threshold using some magic numbers and the variance
double thresh = (-0.0025714 * variance) + 1.5142857;
thresh *= thresholdModifier;
//if the any sample is threshold percent larger than the average, then we mark it as a beat.
for (int j = 0; j < partitionSize; j++) {
if (data[i+j] > thresh * avg) {
_beatList.AddBeat(((float)(i + j) / data.Length) * clip.length, 1f, data[i + j]);
}
}
}
//eliminate double positives (the same beat occurring in two overlapping partitions, for example) by removing beats with extremely similar timestamps
for(int i = 0; i < _beatList.beats.Count-1; i++) {
if((_beatList.beats[i+1].timeStamp - _beatList.beats[i].timeStamp) < .1) {
if(_beatList.beats[i + 1].energy > _beatList.beats[i].energy) {
_beatList.beats.RemoveAt(i);
}
else {
_beatList.beats.RemoveAt(i + 1);
}
i--;
}
}
return _beatList;
}
/// <summary>
/// Writes a beatmap to xml file from BPM and song length.
/// </summary>
/// <param name="name">Xml file name.</param>
/// <param name="bpm">Beats per minute.</param>
/// <param name="numBeats">Number of beats.</param>
public static void BeatMapFromBPM(string name, float bpm, int numBeats)
{
float beatStep = 60f / bpm;
float length = (float)numBeats * beatStep;
BeatMap beats = new BeatMap(name, length);
for (float i = 0f; i < length; i += beatStep) {
beats.AddBeat(i, 1f, 1);
}
BeatMapSerializer.BeatMapWriter.WriteBeatMap(beats);
Debug.LogFormat("Coda: Created beatmap {0} with BPM of {1} and running time of {2} seconds ({3} beats long).", name, bpm, length, numBeats);
}